The Fe-B-R base magnets have attracted public attention as a novel permanent magnet with a high-performance using rare earth elements (R) represented by Nd, Pr etc. They have prominent advantages that they exhibit characteristics comparable to those of a conventional high-performance magnet, e.g., the Sm-Co base magnet, do not require expensive and scarce Sm as R and do not necessarily use expensive Co which is difficult to be procured steadily, as disclosed in JP Patent Kokai No. 59-46008 or EP 0101552. Particularly, Nd has been hitherto regarded as having no utility value. Therefore, it is very valuable for industry that Nd can be used as a principal element.
Recently, it has been attempted to provide high magnetic characteristics for the Fe-B-R base magnets and to produce them at lower costs. For example, the applicants' company developed a high-performance magnet using, as R, Nd and/or Pr mainly, and partly at least one of Gd, Tb, Dy, Ho, Er, Tm and Yb (hereinafter, these elements are referred to as R.sub.1), and filed a patent application thereon (JP Application No. 58-140590, now JP Patent Kokai No. 60-32306 or EP 0134305).
In the JP Patent Kokai No. 60-32306, it was proposed that the superior R.sub.1 -R.sub.2 -Fe-B base rare earth magnets (wherein R.sub.1 represents the same as hereinabove mentioned, and R.sub.2 represents that the sum of Nd and/or Pr is at least 80 atomic % and the balance in R.sub.2 is at least one of rare earth elements R other than R.sub.1) are produced by substituting at least one of heavy rare earth elements R.sub.1 for at most 5 atomic % of rare earth element such as Nd, Pr, etc. in the R-Fe-B base or R-Fe-Co-B base rare earth magnets. These superior R.sub.1 -R.sub.2 -Fe-B base rare earth magnets enable to prominently raise the coercive force (iHc) to 10 kOe or more and to be used at 100.degree.-150.degree. C., i.e., temperatures higher than room temperature, while maintaining a high energy product of (BH) max of at least 20 MGOe. As starting materials for the production of R.sub.1 -R.sub.2 -Fe-B base rare earth magnets, primarily there are used expensive bulk or lump metals having little impurities, such as electrolytic iron with a purity of at least 99.9%, and rare earth metals with a purity of at least 99.5% prepared by an electrolysis or a heat reduction.